1. Field of the Invention
The present invention generally relates to an air conditioning system, such as for use in cooling and heating passenger compartments in automotive vehicles, and more particularly, to an air conditioning system having a heat exchanger accelerating system for more efficiently cooling and heating automobile passenger compartment.
2. Description of the Related Art
A heat pump circuit may be used in an automobile air conditioning system to improve the cooling and heating efficiency of the system in the outside air inlet mode of operation. For example, Japanese Patent Application No. 62-181909 describes an automobile air conditioning system that includes a heat pump circuit. When the heat pump circuit is used for heating, a first heat exchanger is disposed in the passenger compartment and is used as a condenser. A second heat exchanger is disposed in the engine compartment and is used as an evaporator.
FIG. 1 illustrates a heat pump-type automotive air conditioning system. Air conditioner 100 includes a variable displacement motor compressor 1, an external heat exchanger 3, and an internal heat exchanger 4. Air for air conditioning is conducted into the interior of the vehicle through a duct 10. External heat exchanger 3 is positioned outside of duct 10, and internal heat exchanger 4 is positioned inside of duct 10.
First, second, third, and fourth openings of four-way valve 2 are connected to the discharge port of compressor 1, a first port of internal heat exchanger 4, the suction port of compressor 1, and a first port of external heat exchanger 3, respectively. A second port of external heat exchanger 3 is connected to the inlet of a receiver 9 via a first check valve 7. The outlet of receiver 9 is connected to internal heat exchanger 4 via a first expansion valve 5. A second expansion valve 6 is provided between the outlet of receiver 9 and the second port of external heat exchanger 3. Further, the second port of internal heat exchanger 4 is connected to the inlet port of receiver 9 via a second check valve 8.
Duct 10 has an outside air inlet port and an inside air inlet port. The balance between outside air and inside air to be drawn into duct 10 is adjusted by a switching damper 12. A motor fan 11 is positioned in duct 10 as a means for drawing outside air into the interior of the vehicle.
In FIG. 1, the solid arrows indicate the direction of refrigerant flow when the heat pump circuit is used for cooling air, and the dashed arrows indicate the direction of refrigerant flow when the heat pump circuit is used for heating. In operation, in response to a demand to cool passenger compartment, four-way valve 2 is switched (solid lines in valve 2) to configure the heat pump circuit as an air cooling system.
When air cooling is performed, the refrigerant is circulated from compressor 1 via four-way valve 2 to the first port of external heat exchanger 3, from the second port of external heat exchanger 3 to the inlet of receiver 9 via check-valve 7, from the outlet of receiver 9 via expansion valve 5 to the second port of internal exchanger 4, and from the first port of internal heat exchanger 4 via four-way valve 2 to compressor 1, as shown by the solid line arrows in FIG. 1. The inside, e.g., recycled, or outside, e.g., fresh, air is introduced into duct 10 through damper 12 and passes through internal heat exchanger 4 due to the operation of motor fan 11. In this configuration, internal heat exchanger 4 is utilized as an evaporator. Consequently, the inside or outside air exchanges heat with the refrigerant in internal heat exchanger 4, and the refrigerant vaporizes due to its absorption of heat from the inside or outside air. As a result, the inside or outside air, which is thus cooled, is blown into passenger compartment 13, whereby passenger compartment 13 is cooled. Subsequently, the air in passenger compartment 13 is vented to the outside of the automobile through ventilation duct 14.
Alternatively, when air heating is performed, the refrigerant is circulated from compressor 1 via four-way valve 2 to the first port of internal heat exchanger 4, from the second port of internal heat exchanger 4 via check valve 8 to the inlet of receiver 9, from the outlet of receiver 9 via expansion valve 6 to the second port of external heat exchanger 3, and from the first port of external heat exchanger 3 via four-way valve 2 to compressor 1, as shown by the dashed line arrows in FIG. 1. The inside or outside air again is introduced into duct 10 through damper 12 and passes through internal heat exchanger 4 due to the operation of motor fan 11. In this configuration, internal heat exchanger 4 is utilized as a condenser. Consequently, the inside or outside air exchanges heat with the refrigerant in internal heat exchanger 4, and the refrigerant is condensed due to its loss of heat to the inside or outside air in duct 10. As a result, the inside or outside air, which is thus heated, is then blown into passenger compartment 13, whereby passenger compartment 13 is heated. Subsequently, the air in passenger compartment 13 is vented to the outside of the vehicle through ventilation duct 14.
Thus, such air conditioning system results in the loss of energy, represented by the calories expended in heating or cooling air blown into the passenger compartment, which the air that is vented outside of the vehicle includes implicitly. The air conditioning system loses this energy outside of the vehicle when the system exhausts unpleasant, e.g., too hot or too cold, and stale air to the outside of the vehicle. Therefore, such heat pump systems consume additional energy to compensate for this vented air.